This is pretty much an update to this post.
My kid is emotional. She has always, even as a little baby, flipped emotions in a matter of a second. It has always been a source of amusement in our family, how she can go from laughing to crying or crying to laughing in 2 seconds flat.
It is hilarious how she can compose herself when she is a "sad baby."
Lately she has been throwing these little tantrums where she screams and cries and carries on. When this happens, I tell her, "Go to your room and find a happy face." She will usually run back to her room and look in the mirror by her crib.
The first time I said this to her, I showed her where to go to find her happy face. The second time I told her this, she took off down the hall. I snuck back to her room and saw her making faces at herself in the mirror. She spotted me pretty quick and started laughing. Now when I tell her this, she runs down the hall and runs back a moment later with a huge smile, saying, "Mommy, baby happy now!"
Also, she'll sometimes cross her arms and scrunch up her face and say, "Baby so mad." This is a far cuter way to express those feelings, girlfriend. It is even cuter when she pretends to be mad and can't hold back her smile!